Re: Jay Bruce looks like he has become a professional hitter overnight!!!!!!!
If I had to guess, I would say Bruce is working to try to stop pulling off the ball. I don't think it's a change in approach, just a determined effort to keep the shoulder in, wait on the ball and take it the other way -- not as a desired result, exactly, but as a means to a greater end (not pulling off the ball so badly). I suspect as he gets more comfortable, we'll see him stop the deliberate effort to go the other way and move back to a more natural swing. Eventually he will start pulling off again and he again will make the concerted effort to go to left field to try to correct it. It will be a constant adjustment.
Many hitters go through this. Barry Larkin was open in talking about how when he was struggling, he would make a conscious effort to go the other way -- not because he was searching for more hits in right field, but because he felt that was the best way to get his swing where he wanted it.
It seems to me Bruce isn't as proficient at making those kinds of adjustments as a guy like Larkin or Joey Votto, so the process takes longer and can be tougher to watch. But I applaud him for making the effort.